Preheat oven (electric cooker: 225 °C/circulating air: 200 °C/gas: see manufacturer). Peel and finely dice onion and garlic. Clean, wash and cut leek into rings.
Heat the oil in a pan. Fry the minced meat in it until crumbly. Season with salt and pepper. Add onion, garlic and leek and fry briefly.
Deglaze with cream and 200 ml water, bring to the boil. Grate cheese, add approx. 2/3 and melt in the sauce. Season again with salt and pepper.
Spread a little sauce on the bottom of two ovenproof deep plates. Place 3 lasagne plates alternately with chopped sauce on each plate, finishing with chopped sauce. Sprinkle with the remaining cheese. Bake in a hot oven for about 15 minutes.